It's like weird Parasites
10. Swimming blind
The Greenland shark lives in the frozen Arctic seas and almost always carries a large copepod parasite on its eye. A 40mm-long female infects the cornea and sinks a permanent anchor into the eye while she feeds on it. The parasite rubs on the surface of the shark’s eye and eventually blinds the shark. Greenland sharks hunt mainly with their nose and do not seem to suffer. There was a theory that the glow-in-the-dark parasite lured fish towards the shark’s mouth but no evidence for this has ever been found.